Final answer:
The sentence 'The sad sister sat on a silver seat' is an example of alliteration, a literary device characterized by the repetition of the same consonant sound at the beginning of closely connected words.
Step-by-step explanation:
The sentence 'The sad sister sat on a silver seat' is an example of alliteration. Alliteration is a literary device where consecutive words in a sentence start with the same consonant sound. In this case, the 's' sound is repeated at the start of 'sad', 'sister', 'sat', 'silver', and 'seat', which makes it an alliteration.
A metaphor is a direct comparison between two unlike things without using 'like' or 'as'. For instance, saying 'My love, you are a rose' is a metaphor as it equates a person with a rose directly.
On the other hand, a simile is a comparison that uses 'like' or 'as', such as 'My darling, you are like a rose.' This shows similarity between two different things rather than stating one is the other.
Personification is giving human traits to non-human things, such as 'the wind whispered through the trees'.
The sentence in question does not contain a metaphor, simile, or personification. It does not equate the sister with something else directly or indirectly, nor does it attribute human qualities to non-human elements. The imagery used in the sentence focuses on visual description, but the primary literary device is alliteration.